"Molecular and Cellular Targets of Adenosine in Lung" will focus on identifying inflammatory cells that are important for mediating bleomycin toxicity to the lung, and the mechanisms used by agonists of the A2A adenosine receptor (A2AAR) to inhibit lung inflammation. Aim 1A is to characterize cells from genetically modified mice with tissue specific deletions of the A2AAR in bone marrow-derived cells, T cells, granulocytes or endothelial cells (EC). Transcripts for the four adenosine receptor (AR) subtypes will be measured by quantitative RT-PCR in purified neutrophils, macrophages, T cells and lung EC purified. Aim 1B is to phenotype A2AAR responses in cells derived from these mice is functional assays of neutrophils (oxidative burst), macrophages (TNFalpha release and integrin expression), T cells (INFgamma release and adherence) and EC (adherence and adhesion molecule expression) or FACS detection of cell surface activation markers. Hypothesis 1 is that it will be possible to nearly eliminate A2AAR expression and function in cells derived from various genetically modified mice with little effect on the expression other AR subtypes. These studies will be helped by the availability of unique AR subtype selective ligands. Aim 2 is to examine the induction in response to LPS (positive control) and bleomycin of mRNAs induced by inflammation in macrophages and other cells. Induced ARs will be quantified by mRNAs, radioligand binding (where possible), and functional assays. Hypothesis 2 is that functional anti-inflammatory responses to adenosine are strongly induced by inflammatory stimuli. Aim 3 is to determine how bleomycin and A2AAR activation affect leukocyte trafficking, pulmonary cytokine production and fibrosis in vivo using mice with various targeted A2AAR deletions, and mice lacking pulmonary macrophages, INFgamma or CXCR2 receptors (that bind KC or MIP-1alpha). Cell trafficking will be measured by counting cells is BALF, dispersed lung, immunohistochemistry and, in live animals by ultra-high resolution gamma-imaging and MRI. Hypothesis 3 is that the response to A2AAR activation influenced by pulmonary macrophages and/or T cells. These results will be helpful for determining the role of A2AAR activation in protecting lungs from other injuries (LPS and ischemia-reperfusion injury) that are being investigated in the other projects.